a reduced or condensed version of the two common jibes "spaz" and "clarrt", both of which are also shortened forms of insults. Spaz being the shortened version of spastic. Clarrt being the short for of razzclot (razz clot being the Jamaican name forthe chunky part of menstral blood).
Spazzclarrt is used by clever people who are talking to white-wide-boys-who-think-they're-black to
take the piss by introducing a clearly stupid new piece of urban vocabulary in the hope it will be used in the presence of some real bad ass
mother fucker, thereby causing said
wannabe white wide boy to be revealed for the numpty he / she is and leading to their ejection from the group.